Buggy code:
public class VerifierHelper { @ Autowired private SlangCompiler slangCompiler ; @ Autowired private ScoreCompiler scoreCompiler ; private static final Logger log = Logger . getLogger ( SlangFilesVerifier . class ) ; private String [ ] SLANG_FILE_EXTENSIONS = new String [ ] { "sl" , "sl.yaml" , "sl.yml" } ; private Map < String , Executable > slangModels = new HashMap < > ( ) ; private Map < String , CompilationArtifact > compiledArtifacts = new HashMap < > ( ) ; public void verifyAllSlangFilesInDirAreValid ( String directoryPath ) { } private void transformSlangFilesInDirToModels ( String directoryPath ) { <START_BUG> Validate . notNull ( directoryPath , "Directory<seq2seq4repair_space>path<seq2seq4repair_space>path<seq2seq4repair_space>can<seq2seq4repair_space>not<seq2seq4repair_space>be<seq2seq4repair_space>null" ) ; <END_BUG> Collection < File > slangFiles = FileUtils . listFiles ( new File ( directoryPath ) , SLANG_FILE_EXTENSIONS , true ) ; VerifierHelper . log . info ( ( "Start<seq2seq4repair_space>compiling<seq2seq4repair_space>all<seq2seq4repair_space>slang<seq2seq4repair_space>files<seq2seq4repair_space>under:<seq2seq4repair_space>" + directoryPath ) ) ; VerifierHelper . log . info ( ( ( slangFiles . size ( ) ) + "<seq2seq4repair_space>.sl<seq2seq4repair_space>files<seq2seq4repair_space>were<seq2seq4repair_space>found" ) ) ; for ( File slangFile : slangFiles ) { Validate . isTrue ( slangFile . isFile ( ) , "filePath<seq2seq4repair_space>must<seq2seq4repair_space>lead<seq2seq4repair_space>to<seq2seq4repair_space>a<seq2seq4repair_space>file" ) ; Executable sourceModel ; try { sourceModel = slangCompiler . preCompile ( fromFile ( slangFile ) ) ; } catch ( Exception e ) { VerifierHelper . log . error ( ( ( ( "Failed<seq2seq4repair_space>creating<seq2seq4repair_space>Slang<seq2seq4repair_space>,models<seq2seq4repair_space>for<seq2seq4repair_space>directory:<seq2seq4repair_space>" + directoryPath ) + ".<seq2seq4repair_space>Exception<seq2seq4repair_space>is<seq2seq4repair_space>:<seq2seq4repair_space>" ) + ( e . getMessage ( ) ) ) ) ; throw e ; } verifyStaticCode ( slangFile , sourceModel ) ; slangModels . put ( getUniqueName ( sourceModel ) , sourceModel ) ; } if ( ( slangFiles . size ( ) ) != ( slangModels . size ( ) ) ) { throw new RuntimeException ( ( ( ( ( ( "We<seq2seq4repair_space>found:<seq2seq4repair_space>" + ( slangFiles . size ( ) ) ) + "<seq2seq4repair_space>.sl<seq2seq4repair_space>files<seq2seq4repair_space>in<seq2seq4repair_space>path:<seq2seq4repair_space>" ) + directoryPath ) + ".<seq2seq4repair_space>We<seq2seq4repair_space>managed<seq2seq4repair_space>to<seq2seq4repair_space>create<seq2seq4repair_space>slang<seq2seq4repair_space>models<seq2seq4repair_space>for<seq2seq4repair_space>only:<seq2seq4repair_space>" ) + ( slangModels . size ( ) ) ) ) ; } } private void compileAllSlangModels ( ) { } private Set < Executable > getModelDependenciesRecursively ( Executable slangModel ) { } private void verifyStaticCode ( File slangFile , Executable executable ) { } private String getUniqueName ( Executable sourceModel ) { } }

Fix:
Validate . notNull ( directoryPath , "You<seq2seq4repair_space>mut<seq2seq4repair_space>specify<seq2seq4repair_space>a<seq2seq4repair_space>path" ) ;